1. Technical Field
The invention relates to roofing systems and methods of securing insulation to roof decks, and in particular to such a system and method which secures insulation boards to a roof deck free of mechanical fasteners. More particularly, the invention relates to such a system and method in which a flexible waterproof membrane covers the secured insulation boards to provide a weatherproof roof covering.
2. Background Information
Pressure sensitive adhesive tapes have been used in the roofing industry primarily for adhering together flexible roof membrane seams or to adhere the flexible membrane to attaching devices. However, the insulation boards placed between the roof deck and the roof membrane traditionally have been mechanically attached to the roof deck by screws and plates, or sometimes have been secured with hot asphalt.
Mechanical fastening of insulation boards to a roof deck, although effective for securely attaching the insulation thereto, nevertheless requires an external power source for operating tools needed to complete the fastening operation, involves numerous steps from start to finish of the job, and is labor-intensive. Thus, mechanical fastening of insulation boards to a roof deck is a relatively expensive, time-consuming project. Also this use of mechanical fasteners provides a path from the exterior of the roof to the building interior for the undesirable passage of heat and cold known as thermal bridging.
The hot asphalt method of attachment has several disadvantages, most notably that hot asphalt damages or does not adhere to some insulation board types, and currently violates certain building code requirements as a fire hazard. In addition, asphalt attachment is relatively expensive, time-consuming, and messy since it requires kettles fired by fuel and mops for applying the asphalt to the roof deck.
U.S. Pat. No. 3,468,086 discloses a prefabricated roofing construction in which edges of roofing panels are provided with an adhesive material which is located on a foldable tape portion which is unfolded to overlay an adjacent section and to attach the sections to each other.
U.S. Pat. No. 3,708,379 discloses an elastomeric tape in which each of two bands comprises a portion of the elastomer and of the curing system. The elastomeric tape preferably is made of uncured copolymer elastomer, such as butyl rubber. In addition to butyl rubber and curing system components, the bands of the tape may contain plasticizers, fillers and pigments.
U.S. Pat. No. 3,900,999 discloses a rubber compound wherein a two-component polymeric tape is produced. A partially vulcanized butyl rubber can be used as the second component of the tape.
U.S. Pat. No. 4,736,917 discloses an attachment device for insulation wherein a double sided adhesive tape is attached to a plate and a protective film on one side of the tape is removed when the device is applied to a wall.
The closest known prior art to the present invention is disclosed in U.S. Pat. No. 4,688,361. This patent discloses a plurality of plates which are mechanically fastened to an underlying roof deck for holding down insulation boards positioned between the deck and plates. Also, the plates contain an adhesive which adheres to the underside of an overlying rubber roof membrane for holding the membrane in position. However, this patent does not disclose the use of flexible pads or strips, preferably formed of butyl rubber, which contain a pressure sensitive adhesive, positioned beneath insulation boards for securing the boards to a roof deck without using mechanical fasteners.
Thus, the need exists for an improved roofing system and method of securing insulation board to roof decks, without using mechanical fasteners.